1. Field of the Invention
Taggants utilizing DNA nucleotide sequences, and methods of making, combining and using such taggants.
2. Description of Related Art
There is an increasing commercial and national need for safe, covert and information-rich marker or “taggant” technology, which can be used in applications such as protecting the public interest, preventing product counterfeiting and piracy, and providing an evidentiary basis to enforce intellectual property rights or defend against unwarranted product liability litigation. There is a need for taggant technology that can generate and detect millions of distinct taggants, and decipher the billons of distinct ways that these taggants can be combined. This need is illustrated in the following broad examples.
The United States Department of Commerce indicates that counterfeiting and piracy cost the U.S. economy between $200 billion and $250 billion per year, are responsible for the loss of 750,000 American jobs, and pose a threat to public health and safety. The FDA alone has seen an 800% increase in the number of new counterfeit drug cases between 2000 and 2006. The Center for Medicine and the Public Interest estimates the sales of counterfeit drugs will reach $75 billion in 2010. The counterfeiting of the drug heparin has been linked to the deaths of between 81 and 149 people in the U.S., and resulted in hundreds of allergic reactions.
Heretofore, a number of patents and publications have disclosed the use of taggant technology, wherein small quantities of certain substances are used as taggants (markers or labels) for tagging, authenticating, tracking, and/or tracing other materials, items, or processes. Among such disclosures are the following, all of which are incorporated herein by reference:
U.S. Pat. No. 5,451,505 to Dollinger discloses methods for tagging and tracing materials using nucleic acids as taggants. In particular, Dollinger discloses a method for tagging a material by treating the material with a nucleic acid taggant so that the nucleic acid attaches to the material in an amount sufficient for subsequent detection. The nucleic acid taggant comprises a specific nucleotide sequence or has a distinct composition of specific nucleotides to facilitate tracing.
International patent application publication WO/2000/061799 of Minton et al. discloses a method of marking a material and subsequently detecting that it has been marked. The method comprises adding or applying a marker comprising a nucleic acid tag to the material, sampling a portion of the material containing the marker, and detecting the presence of nucleic acid tag in the sample. The method is characterized in that the quantity of the nucleic acid tag present in the sample is determined to provide an indication of the quantity of marker present in the material.
U.S. Pat. No. 7,112,445 to Welle discloses a method for identification tagging, and in particular, identification tagging of ammunition. An isotopic taggant is deposited in a layer at the interface between the ammunition primer and propellant so that, as the ammunition is fired, the taggant is dispersed throughout the propellant. The taggant is thus contained in the gunshot residue formed during the firing, and can be read by analysis of residue particles. Reading may be accomplished by employing a binary coding system and a system of authentication tags. The required large number of unique identification tags are obtained by using a fragmented coding system wherein each particle encodes only a portion of an ammunition serial number.
These and other taggant systems notwithstanding, certain problems remain unaddressed in the use of taggants to monitor bulk materials, items, and processes for their manufacture. Depending upon the particular application, a taggant needs to satisfy a broad range of requirements, some of which heretofore have been in conflict with each other. The following is a list of attributes that are desirable in a taggant and/or a set of taggants:    1. Having tens of thousands of unique “signatures” (numerical sequences) in the set of taggants for authenticating, and/or tracking and tracing a large number of targets with a large quantity of aspects (i.e. bits of data).    2. “Deeply layerable,” i.e. it should be possible to tag an object with multiple taggants (either simultaneously or over time), wherein the object has undergone a series of manufacturing process steps, and/or is comprised of multiple materials possibly from multiple production batches, and/or is comprised of items that may be from multiple manufacturing plants or suppliers. These are exemplary characteristics; an object may have other characteristics that can be correlated with taggants. The “layered taggants” can be provided on or in the object to represent its various characteristics. The identity of each of the taggant in the layered collection of multiple taggants must be recoverable from the object, and capable of being detected, and analyzed and decoded such that the object can be authenticated, and/or its production history tracked and traced.    3. Nano-scale (i.e. on the order of nanometers dimensionally). This enables taggants to be applied to extremely small structures or items, as well as being covert.    4. Highly covert, i.e. undetectable to an observer, or even undetectable by analysis when it is known or suspected that a taggant is present, but no knowledge of the taggant nature or code is available.    5. Detectable at a parts-per-trillion concentration. This enables low cost use, in that a very small amount of taggant is required to be applied on or in an object to enable subsequent authentication and/or track and trace. Additionally, this attribute facilitates highly covert use.    6. Efficiently decodable, so that the information contained in a taggant, or layered taggants, is easily and quickly accessed.    7. Inert, non-reactive, so that they can be used in a broad range of environments with no interaction with chemicals, heat, light, etc. that are present in an ambient environment.    8. Ingestible, so that they can be used on ingestible products, such as medications.    9. Environmentally safe, so that in use, they do not contaminate an environment or product to which they are applied.    10. Not harmful to internal combustion engines.    11. Useable in solution. By being soluble in a common liquid medium, they can be easily applied in small quantities by simple dispensing equipment.    12. Useable in solids or on solid surfaces, so that they can be easily integrated into an object, or applied to the object.    13. Inexpensive, so that the cost of the taggant is insignificant compared to the cost or value of the product to which it is applied.
In summary, there is both a market need and, in some instances, a legislative imperative for track, trace-back, and authentication technologies. In the field of pharmaceuticals, for example, the Food and Drug Administration Amendments Act (FDAAA) of 2007 directs the FDA to identify and validate effective technologies for the purpose of securing the drug supply chain and for the development of standards for the identification, authentication, and tracking and tracing of prescription drugs.
It is an extremely challenging problem to provide a taggant or set of taggants that has all of the above attributes, or even a large majority of them, in order to satisfy the stringent requirements of complex applications such as pharmaceuticals. To the best of the Applicant's knowledge, there is no taggant currently available which has all of the above listed attributes. There remains a need for such a taggant for providing protection of products and/or processes in fields such as agriculture, banking, defense, environmental protection, homeland security, law enforcement, consumer products, transportation, and public health.
More specifically, as will be explained subsequently herein with regard to the art of DNA taggant technology, small taggant libraries of DNA taggants having relatively short sequences are of limited use in practical applications; and substantially larger desirable taggant libraries having longer sequences needed for bit depth (information content) are extremely difficult to synthesize and are cost-prohibitive. What is needed in this art is a set of DNA taggants that are sufficiently short that they can be provided cost-effectively, while also containing the desired large amount of information in a particular application.